Conventionally, developments of various types of heating implements, which produce heat by oxidation reaction of an oxidizable metal, have been made. In particular, moist heat is useful in more effectively transferring heat to the human body, as compared with dry heat of a hand warmer, and therefore developments of vapor heating implements that can generate vapor continue. Patent Document 1 discloses a vapor heating implement, which comprises a unit for generating vapor heat and a water-retention sheet that is disposed to be adjacent to the unit for generating vapor heat.